Selective thermal treatment of skin irregularities such as treatment of vascular lesions, removal of unwanted hair or improving skin texture is commonly used in aesthetic medicine. In order to be destroyed, the target the must be raised to a temperature of about 70° C. without raising the temperature of the epidermis or dermis to damaging levels. The most popular method of thermal skin treatment is selective photo-thermolysis in which light energy produced by a laser or flash lamp is used. However, in many cases it is not possible to heat the skin irregularity to a temperature necessary for destroying it without heating the surrounding skin to damaging levels. The main problem is that he optical contrast between the skin irregularity and the surrounding skin tissue is often not high enough to obtain a significant difference in temperature between the skin irregularity and the surrounding skin tissue. In these cases, another form of energy should be found to provide selective heating of skin irregularity without damaging the surrounding tissue.
U.S. Pat. No. 5,755,753 discloses use of the radio-frequency (RF) range of electro-magnetic energy for skin tightening, where RF energy is applied to a pre-cooled skin surface. U.S. Pat. No. 5,846,252 discloses treating hairs to reduce their electrical resistance and then applying RF current.